VoIPowering Your Office: Roaming the VoIP Wi-Fi World

Today's handsets are up to the task, but availability of local
service is still spotty at best.

In the first three parts of this series we have wandered widely over the whys,
wherefores, and hows of voice over Wi-Fi. Today we're wrapping up our VoIP Wi-Fi
phone overview with a look at multi-mode portable devices: combination cell
phones/Wi-Fi phones/Web browsers/PDAs/kitchen sink devices that fit in a pocket.
Sometimes a large pocket, but still a pocket.

Dual-mode phones: cellular + Wi-Fi
You don't have to make a choice between cellular or Wi-Fi, or carry around masses
of gadgets, because now you can have all these different protocols stuffed into
a single phone. There are two categories of dual-mode cellular+Wi-Fi phones:
Smartphones, which are phone + PDA (Personal Digital Assistant) combos, and
plain old dual-mode phones that just make and receive phone calls.

The Nokia E61 (Europe) and E61i (USA) is one of the elite multi-mode smartphones,
possibly the elitest. It supports quad-band GSM (850-, 900-, 1800- and 1900-MHz)
so it's capable of world roaming. All you do is swap in different SIMs for different
service providers to take advantage of the best rates.

It supports 802.11a/b/g Wi-Fi with WEP/WPA/WPA2 security, and comes with a
SIP client for wireless VoIP. (Remember, WEP is a fairly weak security systemalways
use WPA or WPA2.) The E16/16i also comes with all of the usual goodies: Web
browser, e-mail, instant messaging, texting, a nice keyboard, voice recorder,
media player, camera, expandable storage, provisioning and management over your
network, and gobs moreall crammed into this little gadget. The E61/61i is
readily available unlocked, so you can use it with any cellular carrier, and
hook up to any wireless network for VoIP. It has a neat little "Wireless Wizard"
to help you connect when you're traveling.

Watch out when you're looking at these fancy smartphonesmany of them boast
of being dual-mode cellular plus Wi-Fi, but most of them do not support voice
over Wi-Fi, just wireless Internet. Which is a nice thing if you happen to be
yakking and Web-surfing at the same time, but it's not VoIPyou need a SIP
client for that. You can get add-on Skype client software for several models
of the Blackberry; it's called WebMessenger
Mobile. Jajah is a Web-based VoIP service
that works via any Web browser, so it should work on all Wi-Fi-enabled PDAs
and smartphones that have Web browsers. Unfortunately, Jajah's call quality
usually leaves a lot to be desiredbut it's worth trying.

Not-so-smart phones
There seems to be a wider variety of not-smart dual-modes phones, but beware
of terminology confusion. Dual-mode refers to cellular + wireless VoIP, and
it is also used in connection with cordless VoIP phones. For example, Linksys
and Netgear both have dual-mode cordless Skype phones (DECT or Wi-Fi plus PSTN).
These won't do you much good on the road, but they're convenient as corded desk
phone replacements.

The UTStarcom GF-210, Pirelli DualPhone DP-L10, and the D-Link V-Click Dual-Mode
Phone are three examples of the booming dual-mode GSM/SIP phone market. The
UTStarcom and the Pirelli have settings for wireless preferred or cellular preferred,
and will switch automatically according to what is available. Or you may select
wireless-only or cellular-only. The D-Link phone has a button for manual switching.
All three accept SIMs for easy traveling.

If you're a world traveler you really want a quad-band phone, or one that supports the 850/900/1800/1900 frequency bands. Of course these cost more. You can save money on a tri-band phone, but you have to be careful what you get. Tri-band 850/1800/1900 is best for North America, and 900/1800/1900 for Europe and parts of Asia.

Movin' on
What many users dream of are cellular and Wi-Fi services that interoperate seamlessly,
switching back and forth as conditions warrant and never missing a call or noticing
anything amiss. But we're not quite there yet. The necessary switching-technology
issues have been solved by several solution providers, but most of these solutions
are service-provider centric (that is, the equipment is deployed in the service
provider's network), and the carriers just haven't adopted them yet.

Voice-over-Wi-Fi roaming within a wireless network is possible, but unless
the WLAN in question is one of a number of proprietary centrally managed systems,
the experience is likely to be choppy at best. Wi-Fi roaming across networks
is even farther in the future, since there is no universal standard for roaming
between WiFi networks. This, too, will most likely depend on cooperation between
service providers. So, don't expect to be able to drive and talk via Wi-Fi connectoins
any time soon, as you can with cell networks today. (But then, you shouldn't
drive and talk anyway.)

Locked and unlocked phones
Some phones are sold as "locked," which means it works only with a single carrier's
network. Unlocked phones can change networks simply by changing SIM cards. This
is slick for globetrotting, because taking advantage of local networks and rates
is as easy as swapping SIMs. You can't do this with a locked phone. Usually
you'll get a substantial discount (or subsidy) on a locked phone, so figuring
out the best deal is just a question of mathdo you pay more now, or pay
more later?

That wraps up our look at wireless VoIP. Executive summary: Right now we're
in the early-adopter, bleeding-edge phase.

Bold prediction: Wireless VoIPespecially with the adoption of WiMAX, the
long-range broadband wireless standardwill someday dominate over old-fashioned
cellular networks. It offers the potential of better security, and it will penetrate
into rural areas where cellular providers don't like to go, so we'll get better
coverage. We'll finally start to see genuine video phones and high-quality streaming
services, even to small devices like phones. If you need an excuse to justify
purchasing some cool gear, it won't hurt to starting getting familiar with Wi-Fi
VoIP.